How to Megger a Submersible Pump Motor
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- čas přidán 7. 01. 2019
- Meggers are used for quickly troubleshooting a Well pump motor's resistance to ground. Chris shows you how to megger a motor and explains why it is far superior to testing with a standard ohmmeter.
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Thank you i was having a hard time in class to understand it but now it makes more sense to me.
GET ON WITH IT !!!!
Note with a megger you are not only testing with a more sensitive (meg ohms, gig ohms) instrument, but you are also testing under a more strenuous (similar to in-service) load... Wire insulation is rated for some voltage higher than it may be used at (e.g. 600V rated wire on a 240V pump motor circuit), above which it may break down (even when new). The megger produces a low current but higher voltage (e.g. 250V to 5kV) to put the insulation "under load" to test whether it is breaking down. The 1.5V or 9V battery inside a typical ohm meter is too little to load/stress test for insulation break down. Testing components under load is a tenet of good troubleshooting. For example, a capacitor may read good/ normal value on a cheap tester, possibly fooling the tech into thinking it's a good component. But under rated voltage, say 500V, it may break down to near zero farads, indicating that it is actually bad when operated in circuit. I've picked up many new components from supply only to find some of them too fail under load. It's best to test even new components under load when you can before installing 550 feet down a well, only to have to pull it up again.
OL = open loop while on Resistance scale. That does assume no voltage on circuit you are reading. Nice video!
Good catch!
Make sure to megger line to line as well. A good motor will have a dead short (0.0 Mohm) showing the winding is intact. On a 3 phase set up any way
Very Useful !
Glad it was helpful!
Very nice info... in a pinch you can use a test lightbulb in series with the motor winding to ground and L1 120 or 220 vac any current is questionable? thanks a lot.. 😊
Great content 👌! Thank u
My pleasure!
Thank you for your videos! I am new to the well water industry and have been working as a pump tech here in Michigan, so I have been utilizing your videos to help learn little tips and tricks. I do have one question. When I ohm out my main winding's...let say on a a franklin electric single phase 4" 2 wire, 230v, I should expect 4.2-5.2 per my AIM manual. What does a low Ohm reading mean? Broken down windings, melted, etc.... And on the obverse would I ever see a higher reading, higher than 5.2, and if so, what does that mean? Thank You!
As a pump tech for 30 yrs, Chris has excellent info, I use an 0hm meter, amp meter and continuity tester ,mostly the later two 99% of the time. Fast and accurate for what you need, no need make it too complex. I don,t own a meggar, and honestly don,t know a tech that has one. As he says in his video, ohm meters are not that reliable, to many variables, unknown hp, wire sizes, splices, pump brands, ages and length of wire runs. High amperage with proper voltage = pump pull. Then check it again for mechanicals. No continuity, dead short, short to ground=pump pull. Once the pump is out, cut it loose, check it again on the motor leads. Same results, new pump motor at a minimum. If pump checks out, look at sub cable. Its great if you can identify the exact issue but you can waste a lot of time and energy trying to find the exact failure point. It all equals a pump pull. I've worked on 1/3 hp to 150 hp submersibles, turbines, single phase and 3 phase. Mostly 10 hp and below. If I did big stuff all the time, I would get a meggar. Sounds like you are going to do great.
If the windings have a short (fused or melted together), the resistance will be less than 4.2 ohms.
If the windings have a broken connection, the resistance will be greater than 5.2 ohms.
In either case, the motor is junk and needs to be replaced.
I gambled and bought a Chinese digital megger on Ebay. Surprisingly, it works very well, and cost me only $60 or so. You don't need to spend a lot for modern electronics these days.
which brand did you buy i am considering geting a new megger.. is it digital
is there a formula to calculate a reading before testing?
Cool! Now show us how to use a megohmmeter to diagnose a faulty sump pump.
It's the exact same process, you clamp the ground wire and megger each other wire. The ohm values are going to be all over the place though due to the wide variety/brands of sump pumps. It might be interesting to experiment on old vs. new of the same models.... we'll add it to the list!
@@RCworstwater What do you set the meter on, what ports do you use?
What model fluke are you using?
Hi Chris. Does the AIM manual strictly apply to Franklin Electric motors or can you use it interchangeably?
The motor tables apply only to Franklin motors but some of the troubleshooting information is interchangeable.
@@RCworstwater Thanks Chris. I am assuming you use mainly or solely Franklin Electric Motors then? And if so, are they what you would consider the best?
Your videos are very helpful for the diy. I purchased a Fluke insulation tester as a result of watching this video. With the pump in the well, I tested the pump using the insulation tester and the reading I got was .01 M ohms. This concerned me although the pump has been working fine since it’s installation in January. So, we pulled the pump, pulled tape off where we had spliced it together, and tested it above ground and got the readings I wanted. It read 550 M ohms when testing each wire to ground. It still shows a good motor. Then spliced wires back together and lowered motor in well. Tested above ground again with motor in well and still got the same results as earlier which was .01 or .02 M ohms. I would like to check it periodically so I can determine when the windings are beginning to break down and to determine when it is getting close to replacing motor. Is the reading I am getting above ground normal? If not, what could be the problem? The submersible pump is about 120 feet down in well. Could it be the wire leading down to the pump? Thanks for your time and any information or suggestions you have would be much appreciated! - JS
John, how were you testing it at the well head - using the ground wire or casing? It sounds like it may have been the casing and your ground wire is nicked somewhere underwater.
I was using the ground wire that runs from the motor to the control box. And I forgot to tell you this but when I pressed the test button on the Fluke insulation tool, I noticed that the DC volts on the meter would not read above 30 DC volts even when I tested using 1000 volts DC. However when I pulled the pump and tested it out of the well everything read what it was supposed to. So, you think it could be a nick on the ground wire? On the ground wire attached to the motor or the ground wire on the drop cable?
@@johnshutt2215 Did you isolate the drop cable from the wire that goes to your control box before you took your reading? You don't want the underground/control box wire to be part of the test at all. It might be better if you call us so there's no miscommunication: 855.329.4519
By the way, if there is a nick in the ground wire, will it hurt the motor if I leave it until I can get some new wire? I believe the wire running down to the pump is a 14 AWG stranded wire. I was thinking of getting 10 AWG solid wire anyway and replace the wire sometime in the future. But if you think moisture is getting to the ground, I should be able to replace it in the next couple of weeks. Thanks again!
R.C. Worst & Co., Inc. I just wanted to give you an update. We did replace the old wire with a 12 gauge wire. We took the old wire placed it in our jacuzzi with water and tested the wire for nicks, cuts, or leaks in the wire and did find that the old wire contained leaks and cuts. We tested the pump above ground first (before lowering it in the well) after splicing the new wire to the pump motor and got the 550 M ohms reading. Then we lowered the pump back in the well with 12 AWG solid copper wire and the test results using the insulation tester did read 550 M ohms again. So, we know the pump tested as a new motor. What I am confused about is that I thought the AIM manual says it should read a little over 2 M ohms for a new pump motor when testing the pump in the well under about 30 feet of water. Am I understanding what the AIM manual says? Is it supposed to test the same submersed in water as it does when testing it above ground (not submersed in water)?
Where do u get a merger at ? I'm sk pump repair lm in Safford arizona
Fluke 1577 look it up on google
Is it possible to megger the motor in the well by using the drop cable?
Great question!
In one instance, touching the multimeter leads to casing he gets OL and says there's no resistance and next time he touches the leads to the casing he says "it completely shorts out" while the meter reads 00.0. Isn't that two different outcomes for touching the meter leads to the same place on the casing? Doesn't OL mean high or infinite resistance?
You are correct, the OL explanation was a mistake. OL means there is zero continuity between the probes.
@@RCworstwater Thanks, I am trying to keep it straight in my head!
Why do you put one the testing leads attached to top of motor cant you just put it on the ground wire?
I’m not a plumber or well expert. But if I pull the pump and it’s 10 years old I think I’d replace the pump even if it’s good at the time. It’s definitely lost 10 years of life.
Abosolutely , if your pulling up by hand 400+ft , you ain’t chancing anything . Wouldn’t want to have to pull it up again for a long time .
👀👀👀🕵👍
It's not clear make video proper way I can't understand
OL does not mean over loaded... it means open loop